Del-ton, and J&T are pretty equal. I have a Del-ton A4 upper kit which I love. It is the same quality of a Stag or RRA at half the price. Remember their are only a handful of manufactures that make AR parts, most of the major manufactures only assemble the parts into a rifle. Del-ton uses the same CMT parts source as Stag (owned by CMT) and RRA. The barrels are also Wilson arms. The only difference is that sometimes Del-ton substitutes CMT for DPMS parts when they get a lower price. A Stag will always use CMT parts come with a better warranty but other than that they are very similar in quality.